LANs which provide a single, central file server for a plurality of users are well known in the art. According to the prior art, a central file server controls a plurality of devices and is controlled by a plurality of users according to many different programs. The central file server must run programs for controlling the print queue, loading data into the print queue, writing data to one or more disks, reading data from one or more disks, writing data to screens of individual users, and many other functions.
The central file server controls programs as directed by one or more users. While one user is running a particular program, another user may desire information about the program or devices controlled by the program. For example, while one user is printing a job, another user may desire to know the status of the printer and of any jobs in the print queue. Using the prior art, when a user desires to know the status of another program, such as a print controller, or of a device, such as a printer, the user is required to address the program or device and poll it for information. The device is then required to provide the information to the requesting user. If the status of the printer or print queue changes a moment later, the user desiring to know the status is not notified Rather, the user is required to poll the printer or printer queue again to determine current status. If a user desires to know information about any other program or device, he is required to individually poll the selected device. Frequently, the user is required to know the individual address, particular protocol, and data formatting scheme for the device and program to which the inquiry is directed.
A significant disadvantage of the prior art is that all requests about network status, program operation, and device information are user driven. Each user desiring information is required to generate the signals requesting information. The programs providing information are required to interrupt their processing to provide the requested information to the user on demand. For a complex network, a user may be required to recall many different codes and protocols for addressing numerous individual devices and programs within the network. The result is that many users are unaware of the status of numerous devices and programs operating on the network. User confusion and frustration result from the lack of information. The network is slowed down if many users communicate with a program while it is running.